The invention relates generally to a catheter system and method for use in intravascular procedures, and more particularly, to a catheter system that can be positioned in a patient""s vasculature to perform ultrasonic ablation, dilatation, and stent insertion.
In typical percutaneous transluminal coronary angioplasty xe2x80x9cPTCAxe2x80x9d procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries in a conventional Seldinger technique. The catheter is advanced through the arteries until the distal end is in the ostium of the desired coronary artery. A guide wire is positioned within an inner lumen of a dilation catheter and then both are advanced through the guiding catheter to the distal end thereof. The guide wire is first advanced out of the distal end of the guiding catheter into the patient""s coronary vasculature until the distal end of the guide wire crosses a lesion to be dilated, then the dilation catheter having an inflatable balloon on the distal portion thereof is advanced into the patient""s coronary anatomy over the previously introduced guide wire until the balloon of the dilation catheter is properly positioned across the lesion. Once in position across the lesion, the balloon, which is made of relatively inelastic materials, is inflated to a predetermined size with radiopaque liquid at relatively high pressure (e.g., greater than 4 atmospheres) to compress the arteriosclerotic plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilation catheter can be removed therefrom. Further details of dilation catheters, guide wires, and devices associated therewith for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,616,652 (Simpson); (U.S. Pat. No. 4,638,805 (Powell); and U.S. Pat. No. 4,748,982 (Horzewski et al.).
A major problem which can occur during balloon angioplasty procedures is the formation of intimal flaps which can collapse and occlude the artery when the balloon is deflated at the end of the angioplasty procedure. Another major problem characteristic of balloon angioplasty procedures is the large number of patients subject to re-stenosis in the treated artery. In the case of re-stenosis, the treated artery may again be subjected to balloon angioplasty or to other treatments such as by-pass surgery, if additional balloon angioplasty procedures are not warranted. However, in the event of a partial or total occlusion of a coronary artery by the collapse of a dissected arterial lining after the balloon is deflated, the patient is put in a dangerous situation requiring immediate medical attention, particularly in the coronary arteries.
A major focus of recent development work in the treatment of heart disease has been directed to endoprosthetic devices called stents. Stents are generally cylindrically shaped intravascular devices which are placed within a damaged artery to hold it open. The device can be used to prevent re-stenosis and to maintain the patency of a blood vessel immediately after intravascular treatments. In some circumstances, they can also be used as the primary treatment device where they are expected to dilate a stenosis and then are left in place.
Devices and methods for the rapid and effective delivery of a stent to the desired location within the patient""s vasculature have been developed. Two basic methods and systems have been developed for delivering stents to desired locations within body lumina. One method and system involves compressing or otherwise reducing the diameter of an expandable stent, disposing the compressed stent within a lumen provided in the distal end of a tubular catheter, advancing the catheter through the patient""s vasculature until the distal end of the catheter is immediately adjacent the desired vascular location, and then pushing the stent out the distal end of the catheter into the desired location. Once out of the catheter, the compressed stent expands or is expanded to thereby hold open the artery or other body lumen into which it is placed. The stent is left in the artery, either temporarily or permanently, at the site of a dilated lesion.
The following references illustrate various types of stents and stent delivery systems. The list is meant to be exemplary, not exhaustive on the subject.
However, in some cases it has been found that the above methods cannot be performed. For example, where the target lesion is distal to a 50% or greater stenosis that cannot be pre-dilated, or a target lesion is located proximal to untreatable areas of significant flow compromising disease, the above methods have been unusable. As another example, the above methods have little application where there exists a resistant lesion (fibrotic or calcific) that cannot be pre-dilated. In such a case, the lesion would be resistant to complete balloon inflation at 20 atmospheres. In yet another example, the above methods have had limited or no value in patients judged to have a lesion that prevents complete inflation of an angioplasty balloon.
It has been known that ultrasonic energy may be applied to occlusions to ablate particularly difficult occlusive material from a body lumen thereby opening a larger lumen for later use with a dilatation balloon. However, this approach involves threading at least two catheters through the vascular system of the patient, prolonging the procedure, and providing more trauma to the patient.
In the use of ultrasonic ablation catheters, often multiple lesions will be treated within a single operation. This requires that the guide wire and catheter be repeatedly advanced through narrower and more tortuous arteries. This may require exchanging the guide wire for one or more guide wires appropriate to the new location, or reshaping the distal tip of the existing guide wire before continuing with the procedures.
Exchanging the guide wire in previous catheter designs poses difficulties. The entire therapeutic catheter must be withdrawn, which is difficult and time consuming, requiring reinserting the assembly back to its original location. Previous methods of removing the guide wire while leaving the catheter in place require reinserting the wire along side the catheter and inserting the guide wire into a side port in the assembly. While effective, this also can be time consuming and difficult.
Hence, those skilled in the art have recognized a need for an apparatus and method that can apply ultrasonic energy, dilatation, and a stent with a single device to reduce trauma to a patient. Additionally, a need has been recognized for a device and method that can overcome the above examples of occlusions that prevent the application of dilatation and stent devices so that treatment is possible. In particular, it would be of value to provide a system and method to pre-treat such occlusion examples so that a lower pressure dilatation balloon may be used for dilation prior to placement of a stent device. Additionally, those skilled in the art have also recognized a need for a catheter system and method that can pre-treat occlusions readying them for dilatation devices while at the same time, reducing the trauma to a patient""s vascular system. In conjunction with this need, what has also been heretofore unavailable is an intraluminal lesion removal catheter that provides for the easy and rapid exchange of the guide wire. The invention addresses these needs and others.
Briefly and in general terms, the invention is directed to a medical catheter system for recanalization of a tubular anatomical structure, such as a blood vessel, the catheter system comprising an elongate flexible catheter body having a distal end and a proximal end, an ultrasonic delivery device mounted at the distal end of the catheter body, a dilatation balloon mounted at the distal end of the catheter body, a stent mounted at the distal end of the catheter body such that it may be delivered to the tubular anatomical structure by the distal end of the catheter body, a first lumen disposed longitudinally within the catheter body extending from the proximal end to the distal end and in fluid communication with the dilatation balloon for conducting expansion control fluid to the balloon, and an ultrasound transmission member extending longitudinally through the catheter body from the proximal end and mounted to the ultrasonic delivery device, the transmission member configured to transfer ultrasonic energy to the ultrasonic delivery device.
In more detailed aspects, the ultrasonic delivery device comprises a distal head rigidly mounted to the distal end of the catheter body such that longitudinal and radial movement of the distal head only occurs with like movement of the distal end of the catheter body. The catheter system further comprises a second lumen disposed longitudinally within the catheter body extending from the proximal end to the distal end, the second lumen having a size large enough to accept a guide wire extending into the catheter from the proximal end of the catheter body and to permit the extension of the guide wire distally beyond the distal end, whereby a guide wire may be entirely removed from the catheter body and replaced by another guide wire without removing the catheter from the anatomical structure.
In yet further aspects, the ultrasonic delivery device comprises a guide wire aperture extending completely through the distal head through which the guide wire may be located, the aperture having a size large enough so that the guide wire may be completely retracted through the distal head so that the guide wire may be exchanged with another. The stent is mounted to the outside surface of the balloon such that expansion of the balloon into contact with the tubular anatomical structure delivers the stent into a selected location at the tubular anatomical structure. The catheter system further comprises a radiopaque marker disposed at a selected location on the catheter body. Further, the catheter system also comprises a protective sheath disposed over the stent and the dilatation balloon, the sheath being movable in an axial direction to selectively uncover the stent to allow delivery of the stent to the tubular anatomical structure.
In other aspects, the catheter body includes a guide wire port formed in the catheter body at a location between the proximal and distal ends for locating a guide wire. The catheter system further comprises a second lumen disposed longitudinally within the catheter body extending from the proximal end to the distal end, the second lumen having a size large enough to accept a guide wire extending into the catheter from the proximal end of the catheter body and to permit the extension of a guide wire distally beyond the distal end of the catheter wherein the ultrasonic delivery device comprises a distal head rigidly mounted to the distal end of the catheter body such that longitudinal and radial movement of the distal head is not possible without like movement of the distal end of the catheter body, the distal head having a guide wire aperture aligned with the second lumen, the aperture having a size large enough so that the guide wire may be completely retracted through the distal head so that the guide wire may be exchanged with another, whereby a guide wire may be entirely removed from the catheter body and replaced by another guide wire without removing the catheter from the anatomical structure.
In more detailed aspects of a method, the method for recanalization of a tubular anatomical structure, such as a blood vessel, comprises the steps of advancing an elongate flexible catheter body having a distal end and a proximal end to a lesion in the tubular anatomical structure, applying ultrasonic energy to the lesion with the distal end of the catheter body to ablate the lesion, crossing the lesion with a guide wire, crossing the lesion with a dilatation balloon mounted at the distal end of the catheter body, dilating the lesion with the dilatation balloon, delivering a stent to the dilated lesion from the distal end of the catheter body, and withdrawing the catheter from the tubular anatomical structure.
In further detailed method aspects, the method further comprises the steps of removing a first guide wire from the catheter body while retaining the catheter body in place in the tubular anatomical structure, and inserting a second guide wire through the catheter body while it remains in place in the tubular anatomical structure. The method further comprises the step of delivering the stent to the lesion at the same time that the balloon is expanded to dilate the lesion. And yet further, the step of applying ultrasonic energy comprises the step of applying ultrasonic energy with a distal head rigidly mounted at the distal end of the catheter body, the distal head mounted such that longitudinal and radial movement of the distal head occurs only with like movement of the distal end of the catheter body.
These and other aspects, objects, and advantages of the invention will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying drawings.